Battery module assembly of improved reliability and battery pack employed with the same

ABSTRACT

Disclosed herein is a battery module assembly including (a) two or more battery modules having cell units, each of which includes one or more battery cells, connected in parallel to one another, (b) a pair of an upper case and a lower case to surround an upper part and a lower part of the battery modules in a state in which the battery modules are erected on their sides, (c) a bus bar assembly disposed at a front of the battery modules to electrically connect the battery modules to one another in parallel, and (d) a fastening hole formed at a front of the upper case and/or a front of the lower case to position or fix the battery module assembly.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of PCT International Application No.PCT/KR2012/010874 filed on Dec. 14, 2012, which claims the benefit ofPatent Application No. 10-2011-0134170 filed in the Republic of Korea onDec. 14, 2011, all of which are hereby expressly incorporated byreference into the present application.

TECHNICAL FIELD

The present invention relates to a battery module assembly with improvedreliability and a middle or large-sized battery pack including the sameand, more particularly, to a battery module assembly including (a) twoor more battery modules having cell units, each of which includes one ormore battery cells, connected in parallel to one another, (b) a pair ofan upper case and a lower case to surround an upper part and a lowerpart of the battery modules in a state in which the battery modules areerected on their sides, (c) a bus bar assembly disposed at a front ofthe battery modules to electrically connect the battery modules to oneanother in parallel, and (d) a fastening hole formed at a front of theupper case and/or a front of the lower case to position or fix thebattery module assembly.

BACKGROUND ART

Recently, a secondary battery, which can be charged and discharged, hasbeen widely used as an energy source for wireless mobile devices. Inaddition, the secondary battery has attracted considerable attention asa power source for electric vehicles (EV) and hybrid electric vehicles(HEV), which have been developed to solve problems, such as airpollution, caused by existing gasoline and diesel vehicles using fossilfuels.

Small-sized mobile devices use one or several battery cells for eachdevice. On the other hand, middle or large-sized devices, such asvehicles, use a middle or large-sized battery pack having a plurality ofbattery cells electrically connected to one another because high outputand large capacity are necessary for the middle or large-sized devices.

Preferably, the middle or large-sized battery pack is manufactured so asto have as small a size and weight as possible. For this reason, aprismatic battery or a pouch-shaped battery, which can be stacked withhigh integration and has a small weight to capacity ratio, is usuallyused as a battery cell of the middle or large-sized battery pack. Inparticular, much interest is currently focused on the pouch-shapedbattery, which uses an aluminum laminate sheet as a sheathing member,because the pouch-shaped battery is lightweight, the manufacturing costof the pouch-shaped battery is low, and it is easy to modify the shapeof the pouch-shaped battery.

In order for the middle or large-sized battery pack to provide outputand capacity required by a specific apparatus or device, it is necessaryfor the middle or large-sized battery pack to be configured to have astructure in which a plurality of battery cells is electricallyconnected in series to each other or in series and parallel to eachother and the battery cells are stable against external force.

Specifically, when the battery cells are connected in parallel to eachother, electrode terminals of the respective battery cells are connectedto each other by one to one welding at a single weld point.

When three or more battery cells are connected in parallel to oneanother while being stacked, however, three or more connections betweenthe electrode terminals of the battery cells are needed with the resultthat the structure of the battery pack becomes complicated and internalresistance increases when the same region is welded.

Meanwhile, a conventional battery pack is generally manufactured byfixing battery modules to a base plate and using an end plate and asupport bar for a portion of battery modules in order to secure dynamicstability.

However, the battery pack having the above structure has spatiallimitations in mounting the battery modules therein. In a case in whicha large number of battery modules are used to constitute the batterypack, the structural stability of the battery pack is lowered.

In addition, the conventional battery pack is configured to have astructure in which the battery modules are fixed to the base plate usingbolts or nuts such that the battery modules cannot be moved upward anddownward and the battery modules are fixed in the longitudinal directionusing the end plate and the support bar in order to secure dynamicstability.

In the battery pack having the above structure, however, the batterymodules are fixed to the base plate using fastening members, such as aplurality of bolts or nuts with the result that an assembly process iscomplicated and troublesome. In addition, it is necessary to secure aspace for the fastening members, resulting in spatial limitations andweight limitations of the fastening members.

Therefore, there is a high necessity for a battery pack having a compactstructure that is capable of solving the above problems.

DISCLOSURE Technical Problem

Therefore, the present invention has been made to solve the aboveproblems and other technical problems that have yet to be resolved.

Specifically, it is an object of the present invention to provide abattery module assembly configured such that cell units are connected inparallel to each other on a per two battery cell basis using bus bars,thereby improving welding reliability and minimizing internalresistance.

It is another object of the present invention to provide a batterymodule assembly, an assembly process of which is simplified and which isentirely compact and lightweight based on a novel fastening structure tofix battery modules.

Technical Solution

In accordance with one aspect of the present invention, the above andother objects can be accomplished by the provision of a battery moduleassembly including (a) two or more battery modules having cell units,each of which includes one or more battery cells, connected in parallelto one another, (b) a pair of an upper case and a lower case to surroundan upper part and a lower part of the battery modules in a state inwhich the battery modules are erected on their sides, (c) a bus barassembly disposed at a front of the battery modules to electricallyconnect the battery modules to one another in parallel, and (d) afastening hole formed at a front of the upper case and/or a front of thelower case to position or fix the battery module assembly.

That is, in the battery module assembly according to the presentinvention, the battery modules can be coupled between the upper case andthe lower case using a minimum number of members, thereby easilyachieving assembly of a battery pack and thus optimizing the space ofthe battery pack and reducing weight of the battery pack. In particular,in a case in which the battery pack is assembled to have a shelfstructure, such as a rack, it is easy to fix the battery pack, therebysecuring overall structural stability of the battery pack.

In a preferred example, the fastening hole may be configured to have astructure in which a fastening thread is formed at an innercircumference of the fastening hole. Consequently, it is possible toeasily configure the battery pack having the shelf structure by easilyinserting and fastening a member, such as a bolt, into the fasteninghole.

In another preferred example, a depression may be further formed at arear of the upper case and/or a rear of the lower case such that a bartype member to position or fix the battery module assembly can becoupled in the depression.

The depression may be configured to have a structure depressed so as tohave an inside shape corresponding to the outside shape of the bar typemember and may be formed at the rear of the upper case and/or the rearof the lower case in a direction horizontal to a direction in which thebattery modules are arranged. When the bar type member is mounted in thedepression, therefore, the battery modules may be indirectly fixed.

Meanwhile, the battery modules may have cell units, each of whichincludes, preferably, two or more battery cells, connected in parallelto one another.

In addition, each of the cell units may include an even number ofbattery cells. That is, in a case in which the battery modules areconnected in parallel to each other considering capacity of the batterymodules, welding is simultaneously performed at the same region duringwelding between a plurality of electrode terminals or between theelectrode terminals and bus bars, resulting in the increase in internalresistance at the welded region.

In the battery module assembly according to the present invention, onthe other hand, the battery cells of the cell units are connected inparallel to each other on a per two battery cell basis, therebyimproving welding reliability at the welded region. In addition, it ispossible to easily achieve parallel connection based on the even numberof battery cells.

Electrode terminals of the cell units may be electrically connected toeach other via bus bars. Welding may be easily performed based on thecell units including the even number, e.g. two or more, of batterycells.

In a preferred example, the bus bar assembly may include (a) a coverplate formed of an electrically insulative material, the cover platebeing fixed to the front of the battery modules, the cover plateincluding a pair of body parts and (b) a pair of body parts, each ofwhich is configured to have a structure in which an external input andoutput terminal is formed at an L-shaped side thereof and two or morebus bars diverge from the other side thereof in plane in a state inwhich the body parts are mounted on the cover plate, and the body partsmay be arranged so as to face each other in the direction horizontal tothe direction in which the battery modules are arranged.

The body parts may be coupled to the cover plate, preferably, by insertinjection molding.

In addition, the body parts may be provided with steps to prevent ashort circuit between the external input and output terminals of thebattery module assembly. Consequently, the positions of the externalinput and output terminals may be set based on the steps.

Each of the battery cells is a secondary battery having a smallthickness and a relatively large width and length to minimize theoverall size of the battery cells when the battery cells are stacked toconstitute a battery module. In a preferred example, the secondarybattery may be configured to have a structure in which an electrodeassembly of a cathode/separator/anode structure is mounted in a batterycase formed of a laminate sheet including a resin layer and a metallayer and a cathode terminal and an anode terminal protrude fromopposite ends or one end of the battery case. Specifically, thesecondary battery may be configured to have a structure in which anelectrode assembly is mounted in a pouch-shaped case formed of analuminum laminate sheet. The secondary battery having the structure asdescribed above may also be referred to as a pouch-shaped battery cell.

In a preferred example, each of the cell units may be configured to havea structure in which the battery cells are mounted between metalhousings in a state in which the battery cells are in tight contact witheach other.

In the above structure, the metal housings may be coupled to each otherto surround the entirety of an outside of a battery cell stackconstituted by two or more battery cells excluding cathode and anodeterminals of the battery cells. Consequently, the metal housingsrestrain the deformation of the battery cells due to repetitiveexpansion and contraction of the battery cells during charge anddischarge of the battery cells, while protecting the battery cells, themechanical strength of which is low, to prevent sealed portions of thebattery cells from being separated from each other.

Specifically, each of the metal housings may have an internal structurecorresponding to an outside shape of a battery cell stack and, inparticular, the metal housings may be coupled to each other in anassembly fastening fashion. For example, the metal housings may beconfigured to have a male and female fastening structure in whichsection coupling parts of the metal housings are engaged with each otherby elastic coupling when the metal housings are pushed toward each otherin a state in which the metal housings are in contact with each othersuch that the metal housings face each other.

Meanwhile, heat is generated from a secondary battery during the chargeand discharge of the secondary battery and effective discharge of thegenerated heat out of the secondary battery is very important inextending the life span of the secondary battery and securing the safetyof the secondary battery. For this reason, each of the metal housingsmay be made of a metal sheet exhibiting high thermal conductivity, bywhich heat generated from the battery cells mounted between the metalhousings is easily discharged outside.

According to circumstances, insulating tape may be attached to an outercircumference of each of the battery cells excluding the electrodeterminals of each of the battery cells. Consequently, it is possible toprevent destruction of insulation resistance due to contact between thebattery cells and other members, such as the metal housings.

In accordance with another aspect of the present invention, there isprovided a middle or large-sized battery pack of high output and largecapacity including two or more battery modules based on desired outputand capacity.

The battery pack according to the present invention may be manufacturedby combining battery module assemblies based on desired output andcapacity.

In accordance with a further aspect of the present invention, there isprovided a device including the middle or large-sized battery pack.

The device may be an electric vehicle, a hybrid electric vehicle, aplug-in hybrid electric vehicle, or a power storage device inconsideration of installation efficiency and structural stability asdescribed above. However, the present invention is not limited thereto.

DESCRIPTION OF DRAWINGS

The above and other objects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a perspective view showing a battery module assembly accordingto the present invention;

FIG. 2 is an exploded perspective view of the battery module assemblyshown in FIG. 1;

FIG. 3 is a front view of the battery module assembly shown in FIG. 1;

FIG. 4 is a side view of the battery module assembly shown in FIG. 1;

FIG. 5 is a typical view of a cell unit;

FIG. 6 is a partially enlarged view of a battery cell shown in FIG. 5;

FIG. 7 is a typical view of a bus bar assembly; and

FIG. 8 is a typical view showing a pair of body parts shown in FIG. 7.

BEST MODE

Now, preferred embodiments of the present invention will be described indetail with reference to the accompanying drawings. It should be noted,however, that the scope of the present invention is not limited by theillustrated embodiments.

FIG. 1 is a perspective view typically showing a battery module assemblyaccording to the present invention and FIG. 2 is an exploded perspectiveview typically showing the battery module assembly shown in FIG. 1.

Referring to these drawings, the battery module assembly 300 includeseight battery modules 200 having cell units 100, each of which includestwo battery cells 10, connected in parallel to one another, a pair of anupper case 210 and a lower case 220 to surround the upper part and thelower part of the battery modules 200 in a state in which the batterymodules 200 are erected on their sides, a bus bar assembly 230 disposedat the front of the battery modules 200 to electrically connect thebattery modules 200 to one another in parallel, and fastening holes 211and 221 formed at the front of the upper case 210 and/or the front ofthe lower case 220 to position or fix the battery module assembly 300.

FIG. 3 is a front view typically showing the battery module assemblyshown in FIG. 1 and FIG. 4 is a side view typically showing the batterymodule assembly shown in FIG. 1.

Referring to these drawings together with FIGS. 1 and 2, the fasteningholes 211 and 221 are configured to have a structure in which afastening thread (not shown) is formed at the inner circumference ofeach of the fastening holes 211 and 221. Consequently, it is possible tofix the battery module assembly to a predetermined region or apredetermined device by inserting and fastening bolts 250 into thefastening holes 211 and 221.

In addition, depressions 240 and 241 are formed at the rear of the uppercase 210 and the rear of the lower case 220 in a direction (direction Aof FIG. 3) horizontal to a direction in which the battery modules 200are arranged such that bar type members (not shown) to position or fixthe battery module assembly 300 can be coupled in the depressions 240and 241.

FIG. 5 is a typical view of a cell unit and FIG. 6 is a partiallyenlarged view typically showing a battery cell shown in FIG. 5.

Referring to these drawings, the cell unit 100 includes two batterycells 10. Insulating tape 15 is attached to the outer circumference ofeach battery cell 10 excluding electrode terminals 11 to preventdestruction of insulation resistance due to contact between the batterycell 10 and metal housings 120.

Specifically, there is shown a pair of high-strength metal housings 120configured to have a structure to fully surround the outsides of the twobattery cells 10. The metal housings 120 restrain the deformation of thebattery cells 10 due to repetitive expansion and contraction of thebattery cells 10 during charge and discharge of the battery cells 10,while protecting the battery cells 10, the mechanical strength of whichis low, to prevent sealed portions of the battery cells 10 from beingseparated from each other. The metal housings 120 include a left housing121 and a right housing 122, which may be coupled to each other withoutusing an additional fastening member.

FIG. 7 is a typical view of a bus bar assembly according to anembodiment of the present invention and FIG. 8 is a typical view showinga pair of body parts shown in FIG. 7.

Referring to these drawings together with the other drawings, the busbar assembly 230 includes a cover plate 231 and body parts 232.

The cover plate 231 is formed of an electrically insulative material.The cover plate 231 is fixed to the front of the battery modules 200.The cover plate 231 includes a pair of body parts 232. Consequently, theelectrode terminals 11 of the cell units 100 are electrically connectedto each other via bus bars 233.

Each body part 232 is configured to have a structure in which anexternal input and output terminal 234 is formed at an L-shaped sidethereof and two or more bus bars 233 diverge from the other side thereofin plane in a state in which the body parts 232 are coupled to the coverplate 231 by insert injection molding.

The body parts 232 and 232′ are arranged so as to face each other in thedirection (direction A of FIG. 3) horizontal to the direction in whichthe battery modules 200 are arranged.

The body parts 232 are provided with steps to prevent a short circuitbetween the external input and output terminals 234 and 234′.Consequently, the positions of the external input and output terminals234 and 234′ may be set based on the steps.

Although the preferred embodiments of the present invention have beendisclosed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims.

INDUSTRIAL APPLICABILITY

As is apparent from the above description, the battery module assemblyaccording to the present invention is configured such that the cellunits are connected in parallel to each other on a per two battery cellbasis using the bus bars, thereby improving welding reliability.

In addition, the battery modules are fixed through the fastening holesformed at the front of the upper case and/or the front of the lower caseof the battery module assembly, thereby easily achieving assembly of thebattery pack and manufacturing the battery pack with high spatialutilization.

The invention claimed is:
 1. A battery module assembly comprising: (a)two or more battery modules having cell units, each of which comprisesone or more battery cells having electrode terminals, connected inparallel to one another in a first direction; (b) an upper case and alower case to surround an upper part and a lower part of the batterymodules in a state in which the battery modules are erected on theirsides; (c) a bus bar assembly disposed at a front of the battery modulesto electrically connect the battery modules to one another in parallel;and (d) a fastening hole formed at a front of the upper case and/or afront of the lower case to position or fix the battery module assembly,wherein the bus bar assembly comprises: a cover plate formed of anelectrically insulative material, the cover plate being fixed to thefront of the battery modules; a first body part having a first L-shapedsection, a first external input and output terminal formed at one sideof the first L-shaped section and two or more bus bars extending fromanother side of the first L-shaped section; each of the two or more busbars having first and second ends, the first ends connected to theL-shaped section, and the second ends of the two or more bus bars beingfree ends that are spaced from one another; and a second body parthaving a second L-shaped section, a second external input and outputterminal formed at one side of the second L-shaped section and two ormore bus bars extending from another side of the second L-shapedsection, each bus bar having a first end connected to the first L-shapedsection, the second ends of the two or more bus bars being free endsthat are spaced from one another, wherein the body parts are spaced fromeach other in the first direction, wherein the cover plate extends fromthe upper case and the lower case in a vertical direction and from afirst side of the battery case to a second side of the battery case in ahorizontal direction, wherein the cover plate has openings next to thetwo or more bus bars extending from the first body part and the secondbody part, and wherein the electrode terminals of the battery cellsextend through the openings in the cover plate.
 2. The battery moduleassembly according to claim 1, wherein the fastening hole is configuredto have a structure in which a fastening thread is formed at an innercircumference of the fastening hole.
 3. The battery module assemblyaccording to claim 1, wherein a depression is further formed at a rearof the upper case and/or a rear of the lower case such that a bar typemember to position or fix the battery module assembly can be coupled inthe depression.
 4. The battery module assembly according to claim 3,wherein the depression is formed at the rear of the upper case and/orthe rear of the lower case and extends in the first direction.
 5. Thebattery module assembly according to claim 1, wherein the batterymodules have cell units, each of which comprises two or more batterycells, connected in parallel to one another.
 6. The battery moduleassembly according to claim 1, wherein each of the cell units comprisesan even number of battery cells.
 7. The battery module assemblyaccording to claim 1, wherein electrode terminals of the cell units areelectrically connected to each other via bus bars.
 8. The battery moduleassembly according to claim 1, wherein the body parts are provided withsteps to prevent a short circuit between the external input and outputterminals.
 9. The battery module assembly according to claim 1, whereineach of the battery cells is configured such that an electrode assemblyof a cathode/separator/anode structure is mounted in a battery caseformed of a laminate sheet comprising a resin layer and a metal layerand that a cathode terminal and an anode terminal protrude from oppositeends of the battery case.
 10. The battery module assembly according toclaim 1, wherein insulating tape is attached to an outer circumferenceof each of the battery cells excluding electrode terminals of each ofthe battery cells.
 11. The battery module assembly according to claim 1,wherein each of the cell units is configured to have a structure inwhich the battery cells are mounted between metal housings in a state inwhich the battery cells are in contact with each other.
 12. The batterymodule assembly according to claim 11, wherein the metal housings arecoupled to each other to surround the entirety of an outside of abattery cell stack constituted by two or more battery cells excludingcathode and anode terminals of the battery cells.
 13. The battery moduleassembly according to claim 11, wherein each of the metal housings hasan internal structure corresponding to an outside shape of a batterycell stack, and the metal housings are coupled to each other in anassembly fastening fashion.
 14. The battery module assembly according toclaim 11, wherein the metal housings are configured to have a male andfemale fastening structure in which section coupling parts of the metalhousings are engaged with each other by elastic coupling when the metalhousings are pushed toward each other in a state in which the metalhousings are in contact with each other such that the metal housingsface each other.
 15. The battery module assembly according to claim 11,wherein each of the metal housings is made of a metal sheet.
 16. Abattery pack configured to have a structure comprising two or morebattery module assemblies according to claim 1 based on output andcapacity.
 17. A device comprising a battery pack according to claim 16.18. The battery module of claim 1, wherein the two or more bus barsextend in the first direction, and wherein the external input and outputterminal extends in a second direction, the second direction beingperpendicular to the first direction.
 19. A battery module assemblycomprising: two battery modules having cell units connected in parallelto one another in a first direction; an upper case and a lower casesurrounding an upper part and a lower part of the battery modules; a busbar assembly disposed at a front of the battery modules to electricallyconnect the battery modules to one another in parallel; and a fasteninghole formed at a front of the upper case and/or a front of the lowercase to position or fix the battery module assembly, wherein the bus barassembly comprises: a cover plate formed of an electrically insulativematerial, the cover plate being fixed to the front of the batterymodules; an L-shaped body part, the L-shaped body part having a firstsection having a first edge and a second section having a first edgeconnected to the first edge of the first section, the second sectionbeing in a different plane than the first section; an external input andoutput terminal extending outwardly from the first section; and two ormore bus bars extending from the second section, each bus bar having afirst end connected to a second edge of the second section, the secondends of the two or more bus bars being free ends that are spaced fromone another, wherein the cover plate extends from the upper case and thelower case in a vertical direction and from a first side of the batterycase to a second side of the battery case in a horizontal direction,wherein the cover plate has openings next to the two or more bus barsextending from the first body part and the second body part, and whereinthe electrode terminals of the battery cells extend through the openingsin the cover plate.
 20. The battery module of claim 19, wherein theexternal input and output terminal and the second section extend inopposite directions from the first section in a first direction and thesecond section extends from the first section, and wherein the two ormore bus bars and the first section extend in opposite directions fromthe second section.